Electronic origin of hydrogen storage in MOF-covered palladium nanocubes investigated by synchrotron X-rays

Chen, Yanna; Sakata, Osami; Nanba, Yūsuke; Kumara, L. S. R.; Yang, Anli; Song, Chulho; Koyama, Michihisa; Li, Guangqin; Kobayashi, Hirokazu; Kitagawa, Hiroshi

doi:10.1038/s42004-018-0058-3

Cited by 29 publications

(22 citation statements)

References 38 publications

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“…They also reported similar shifts of Pd 3d BE as determined by XPS to higher energies, while concomitantly the Cu 2p BE is lowered. This was attributed to Cu‐O groups acting as electron acceptors [32a] …”

Section: Resultsmentioning

confidence: 99%

Nanoparticles Supported on Sub‐Nanometer Oxide Films: Scaling Model Systems to Bulk Materials

et al. 2021

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Ultrathin layers of oxides deposited on atomically flat metal surfaces have been shown to significantly influence the electronic structure of the underlying metal, which in turn alters the catalytic performance. Upscaling of the specifically designed architectures as required for technical utilization of the effect has yet not been achieved. Here, we apply liquid crystalline phases of fluorohectorite nanosheets to fabricate such architectures in bulk. Synthetic sodium fluorohectorite, a layered silicate, when immersed into water spontaneously and repulsively swells to produce nematic suspensions of individual negatively charged nanosheets separated to more than 60 nm, while retaining parallel orientation. Into these galleries oppositely charged palladium nanoparticles were intercalated whereupon the galleries collapse. Individual and separated Pd nanoparticles were thus captured and sandwiched between nanosheets. As suggested by the model systems, the resulting catalyst performed better in the oxidation of carbon monoxide than the same Pd nanoparticles supported on external surfaces of hectorite or on a conventional Al2O3 support. XPS confirmed a shift of Pd 3d electrons to higher energies upon coverage of Pd nanoparticles with nanosheets to which we attribute the improved catalytic performance. DFT calculations showed increasing positive charge on Pd weakened CO adsorption and this way damped CO poisoning.

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Section: Resultsmentioning

confidence: 99%

Nanoparticles Supported on Sub‐Nanometer Oxide Films: Scaling Model Systems to Bulk Materials

et al. 2021

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“…Auch hier wurde eine Verschiebung des Pd 3d Signals zu höheren BE durch Ladungstransfer festgestellt. Cu‐O Gruppen des MOF wurden dabei als die Ladungsempfänger festgestellt [32a] …”

Section: Ergebnisse Und Diskussionunclassified

Nanopartikel auf subnanometer dünnen oxidischen Filmen: Skalierung von Modellsystemen

et al. 2021

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Durch die Abscheidung von ultradünnen Oxidschichten auf atomar‐flachen Metalloberflächen konnte die elektronische Struktur des Metalls und hierdurch dessen katalytische Aktivität beeinflusst werden. Die Skalierung dieser Architekturen für eine technische Nutzbarkeit war bisher aber kaum möglich. Durch die Verwendung einer flüssigkristallinen Phase aus Fluorhectorit‐Nanoschichten, können wir solche Architekturen in skalierbarem Maßstab imitieren. Synthetischer Natriumfluorhectorit (NaHec) quillt spontan und repulsiv in Wasser zu einer nematischen flüssigkristallinen Phase aus individuellen Nanoschichten. Diese tragen eine permanente negative Schichtladung, sodass selbst bei einer Separation von über 60 nm eine parallele Anordnung der Schichten behalten wird. Zwischen diesen Nanoschichten können Palladium‐Nanopartikel mit entgegengesetzter Ladung eingelagert werden, wodurch die nematische Phase kollabiert und separierte Nanopartikel zwischen den Schichten fixiert werden. Die Aktivität zur CO‐Oxidation des so entstandenen Katalysators war höher als z. B. die der gleichen Nanopartikel auf konventionellem Al2O3 oder der externen Oberfläche von NaHec. Durch Röntgenphotoelektronenspektroskopie konnte eine Verschiebung der Pd‐3d‐Elektronen zu höheren Bindungsenergien beobachtet werden, womit die erhöhte Aktivität erklärt werden kann. Berechnungen zeigten, dass mit erhöhter positiver Ladung des Pd die Adsorptionsstärke von CO erniedrigt und damit auch die Vergiftung durch CO vermindert wird.

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“…Recently, the detailed information on the electronic structure near the Fermi level for Pd@HKUST‐1 was investigated by hard X‐ray photoelectron spectroscopy (HAXPES) measurements at the National Institute for Materials Science (NIMS) beamline BL15XU at SPring‐8, Japan . The HAXPES valence band spectra of Pd@HKUST‐1 showed that 4 ± 2 % electrons transfer from the Pd 4d band to the Cu−O hybridization bands of HKUST‐1.…”

Section: Significantly Enhanced Hydrogen‐storage Capacity and Speed Imentioning

confidence: 99%

“…The HAXPES valence band spectra of Pd@HKUST‐1 showed that 4 ± 2 % electrons transfer from the Pd 4d band to the Cu−O hybridization bands of HKUST‐1. Consequently, the Pd valence in Pd@HKUST‐1 is described as Pd 0.4+ , which corresponds to the additional hydrogen absorption of 0.4H per Pd atom . The charge transfer contribution from the bands near the Fermi level in Pd@HKUST‐1 leads to an increased hydrogen capacity that is approximately twice that of Pd cubes (0.87 H/Pd).…”

Section: Significantly Enhanced Hydrogen‐storage Capacity and Speed Imentioning

confidence: 99%

Hydrogen in Palladium and Storage Properties of Related Nanomaterials: Size, Shape, Alloying, and Metal‐Organic Framework Coating Effects

et al. 2019

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One of the key issues for an upcoming hydrogen energy-based society is to develop highly efficient hydrogen-storage materials. Among the many hydrogen-storage materials reported, transition-metal hydrides can reversibly absorb and desorb hydrogen, and have thus attracted much interest from fundamental science to applications. In particular, the PdÀ H system is a simple and classical metal-hydrogen system, providing a platform suitable for a thorough understanding of ways of controlling the hydrogen-storage properties of materials. By contrast, metal nanoparticles have been recently studied for hydrogen storage because of their unique properties and the degrees of freedom which cannot be observed in bulk, i. e., the size, shape, alloying, and surface coating. In this review, we overview the effects of such degrees of freedom on the hydrogen-storage properties of Pd-related nanomaterials, based on the fundamental science of bulk PdÀ H. We shall show that sufficiently understanding the nature of the interaction between hydrogen and host materials enables us to control the hydrogen-storage properties though the electronic-structure control of materials.[a] Dr.

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Electronic origin of hydrogen storage in MOF-covered palladium nanocubes investigated by synchrotron X-rays

Cited by 29 publications

References 38 publications

Nanoparticles Supported on Sub‐Nanometer Oxide Films: Scaling Model Systems to Bulk Materials

Nanoparticles Supported on Sub‐Nanometer Oxide Films: Scaling Model Systems to Bulk Materials

Nanopartikel auf subnanometer dünnen oxidischen Filmen: Skalierung von Modellsystemen

Hydrogen in Palladium and Storage Properties of Related Nanomaterials: Size, Shape, Alloying, and Metal‐Organic Framework Coating Effects

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